1. A 100-kg astronaut (including the space suit) is stranded in space with only a large bag (50
kg) of asteroid rocks (0.5 kg each). To get back to the exploration vehicle, she’ll have to
throw the rocks in one direction to move in the other. If she can throw 1 rock per second
at a velocity of 30 m/s, what is the specific impulse of her makeshift rocket? What is her
thrust? What total ΔV can she generate?
2. A remote-sensing spacecraft needs to correct its orbital velocity by 10 m/s. If the effective
exhaust velocity of the orbital-maneuvering thruster is 1000 m/s, and the spacecraft’s
initial mass including propellant is 1000 kg, how much propellant will the maneuver
require?
3. Rocket scientists are testing a new three-stage rocket for delivering small payloads to lowEarth orbit. It has these characteristics:
• Ispstage 1 = 300 s
• Ispstage 2 = 350 s
• Ispstage 3 = 400 s
• Payload mass = 1500 kg
• Structure mass stage 1 = 10,000 kg
• Structure mass stages 2 and 3 = 7500 kg each
• Propellant mass stage 1 = 50,000 kg
• Propellant mass stage 2 = 40,000 kg
• Propellant mass stage 3 = 35,000 kg
Find the total ∆V of the launch vehicle.
4. What are three challenges associated with implementing design for manufacturing
throughout a satellite’s life cycle and how might we overcome these challenges?
5. Your SuperSat payload has a critical sensor that needs to operate in order to gather payload
data. Each sensor has a reliability of 95%. Determine the overall reliability of your
system for the following options:
a. Single system (one backup part)
b. Parallel (same design)
c. Diverse design
Which would you implement, assuming you had enough funding for three identical sensors?

Sample Solution